This invention relates to an endoscope and more particularly to a tube for inserting a medical treating instrument such as a forceps and catheter toward a human body cavity.
Generally, a human body cavity is intricately meandered or abruptly turned. When an endoscope is inserted into the body cavity, if a flexible tube is less pliable, there is a fear that the inner wall of the body cavity will be injured, giving pains to a patient. The flexibility of the flexible tube is varied dependent upon the material of the flexible tube, as well as a tube for inserting a medical treating instrument such as forceps and catheter toward the body cavity, image or light guiding fiber bundles etc. all of which are disposed within the flexible tube. However, the image or light guiding fiber bundles are made of a relatively flexible or pliable material. Consequently, the flexibility of the flexible tube is largely dependent upon the tube through which the medical treating instrument is inserted.
A conventional tube for inserting a medical treating instrument toward a body cavity is made of a flexible material and constitutes a single-layer wall, not a multi-layer wall. Some is satisfactory with respect to flexibility or pliability. However, when forceps is inserted through a flexible tube into a sinuous body canal, there are the cases where the tip portion of the forceps abuts against, and bits into, the inner wall of the tube with the result that any further insertion is almost impossible. If at this time the forceps is further forced into the tube, the tube per se is greatly moved within a flexible tube with the resultant injury to the other adjacent members, such as fiber bundles and suction tube disposed within the flexible tube. Furthermore, a lot of time is spent if the instrument is not smoothly inserted through the tube. In some case, the forceps does not extend from the distal end section of the endoscope, making it impossible to observe or examine the body cavity of the patient.
If the tube is made of a relatively rigid material, the inner surface of the tube can be made slippery. However, this advantage is offset by the disadvantage that the flexibility of the tube is sacrificed.